2 * rtc-efi: RTC Class Driver for EFI-based systems
4 * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
6 * Author: dann frazier <dannf@hp.com>
7 * Based on efirtc.c by Stephane Eranian
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the
11 * Free Software Foundation; either version 2 of the License, or (at your
12 * option) any later version.
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/time.h>
19 #include <linux/platform_device.h>
20 #include <linux/rtc.h>
21 #include <linux/efi.h>
23 #define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
25 * EFI Epoch is 1/1/1998
27 #define EFI_RTC_EPOCH 1998
30 * returns day of the year [0-365]
33 compute_yday(efi_time_t *eft)
35 /* efi_time_t.month is in the [1-12] so, we need -1 */
36 return rtc_year_days(eft->day - 1, eft->month - 1, eft->year);
39 * returns day of the week [0-6] 0=Sunday
41 * Don't try to provide a year that's before 1998, please !
44 compute_wday(efi_time_t *eft)
49 if (eft->year < 1998) {
50 printk(KERN_ERR "efirtc: EFI year < 1998, invalid date\n");
54 for (y = EFI_RTC_EPOCH; y < eft->year; y++)
55 ndays += 365 + (is_leap_year(y) ? 1 : 0);
57 ndays += compute_yday(eft);
60 * 4=1/1/1998 was a Thursday
62 return (ndays + 4) % 7;
66 convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
68 eft->year = wtime->tm_year + 1900;
69 eft->month = wtime->tm_mon + 1;
70 eft->day = wtime->tm_mday;
71 eft->hour = wtime->tm_hour;
72 eft->minute = wtime->tm_min;
73 eft->second = wtime->tm_sec;
75 eft->daylight = wtime->tm_isdst ? EFI_ISDST : 0;
76 eft->timezone = EFI_UNSPECIFIED_TIMEZONE;
80 convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
82 memset(wtime, 0, sizeof(*wtime));
83 wtime->tm_sec = eft->second;
84 wtime->tm_min = eft->minute;
85 wtime->tm_hour = eft->hour;
86 wtime->tm_mday = eft->day;
87 wtime->tm_mon = eft->month - 1;
88 wtime->tm_year = eft->year - 1900;
90 /* day of the week [0-6], Sunday=0 */
91 wtime->tm_wday = compute_wday(eft);
93 /* day in the year [1-365]*/
94 wtime->tm_yday = compute_yday(eft);
97 switch (eft->daylight & EFI_ISDST) {
101 case EFI_TIME_ADJUST_DAYLIGHT:
105 wtime->tm_isdst = -1;
109 static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
115 * As of EFI v1.10, this call always returns an unsupported status
117 status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled,
118 (efi_bool_t *)&wkalrm->pending, &eft);
120 if (status != EFI_SUCCESS)
123 convert_from_efi_time(&eft, &wkalrm->time);
125 return rtc_valid_tm(&wkalrm->time);
128 static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
133 convert_to_efi_time(&wkalrm->time, &eft);
137 * As of EFI 0.92 with the firmware I have on my
138 * machine this call does not seem to work quite
141 * As of v1.10, this call always returns an unsupported status
143 status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);
145 printk(KERN_WARNING "write status is %d\n", (int)status);
147 return status == EFI_SUCCESS ? 0 : -EINVAL;
150 static int efi_read_time(struct device *dev, struct rtc_time *tm)
156 status = efi.get_time(&eft, &cap);
158 if (status != EFI_SUCCESS) {
159 /* should never happen */
160 printk(KERN_ERR "efitime: can't read time\n");
164 convert_from_efi_time(&eft, tm);
166 return rtc_valid_tm(tm);
169 static int efi_set_time(struct device *dev, struct rtc_time *tm)
174 convert_to_efi_time(tm, &eft);
176 status = efi.set_time(&eft);
178 return status == EFI_SUCCESS ? 0 : -EINVAL;
181 static const struct rtc_class_ops efi_rtc_ops = {
182 .read_time = efi_read_time,
183 .set_time = efi_set_time,
184 .read_alarm = efi_read_alarm,
185 .set_alarm = efi_set_alarm,
188 static int __init efi_rtc_probe(struct platform_device *dev)
190 struct rtc_device *rtc;
192 rtc = rtc_device_register("rtc-efi", &dev->dev, &efi_rtc_ops,
197 platform_set_drvdata(dev, rtc);
202 static int __exit efi_rtc_remove(struct platform_device *dev)
204 struct rtc_device *rtc = platform_get_drvdata(dev);
206 rtc_device_unregister(rtc);
211 static struct platform_driver efi_rtc_driver = {
214 .owner = THIS_MODULE,
216 .probe = efi_rtc_probe,
217 .remove = __exit_p(efi_rtc_remove),
220 static int __init efi_rtc_init(void)
222 return platform_driver_probe(&efi_rtc_driver, efi_rtc_probe);
225 static void __exit efi_rtc_exit(void)
227 platform_driver_unregister(&efi_rtc_driver);
230 module_init(efi_rtc_init);
231 module_exit(efi_rtc_exit);
233 MODULE_AUTHOR("dann frazier <dannf@hp.com>");
234 MODULE_LICENSE("GPL");
235 MODULE_DESCRIPTION("EFI RTC driver");